Dr Dimitri Diavatopoulos from Radboud University in the Netherlands reported findings of his research on infant mice at the Society for General Microbiology conference in Harrogate, North Yorkshire.
He found that all mice had to be infected with flu for pneumococcal bacteria to efficiently spread between them. Preventing flu infection in the mice stopped the spread of pneumococcal bacteria.
Dr Diavatopoulos said: 'We think the flu virus increases the bacterial load in the nose of colonised individuals but also makes uncolonised individuals more susceptible to pneumococcal infection.'
RCGP immunisation lead Dr George Kassianos said Dr Diavatopoulos's findings fitted with evidence from flu pandemics. 'An important complication of influenza infection is pneumonia,' he said.
He said 29% of patients who died of flu in the 2009 H1N1 pandemic had evidence of bacterial pneumonia caused by Streptococcus pneumonia.
'In addition to the Strep pneumonia, Staphylococcus aureus, group A streptococci and other pathogens can result in pneumonia after influenza infection,' he said.